Systems and techniques to actuate isolation valves

ABSTRACT

A tool that is usable in a well and may include an operator, a switch, a resilient device and an indexer. The switch may be configured to selectively communicate a first force to the operator, thereby actuating the tool. The resilient device may exert a second force. The indexer may cycle through a sequence of positions in response to alternating between the second force and a third force. The sequence includes a predetermined position configured to actuate the switch, thereby communicating the first force to the operator to actuate the tool.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of a related U.S. Non-Provisionalapplication Ser. No. 12/055,456 filed Mar. 26, 2008, entitled “SYSTEMSAND TECHNIQUES TO ACTUATE ISOLATION VALVES”, to Basmajian et al., thedisclosure of which is incorporated by reference herein in its entirety.

BACKGROUND

The invention generally relates to systems and techniques to actuateisolation valves, such as formation isolation valves, for example.

A formation isolation valve may be used in a well for such purposes aspreventing fluid loss and controlling an underbalanced condition. Thevalve forms a controllable sealed access to formations below the valve.When the valve is open, well equipment (a tubular string, a wirelinesystem, a slickline system, etc.) may be deployed through the valve forpurposes of performing one or more testing, perforating and/orcompletion functions below the valve. After these functions arecomplete, the well equipment may be retrieved, and the valve may besubsequently closed.

For purposes of opening and closing the valve, an intervention may beperformed. In the intervention, a tool, such as a shifting tool, is rundownhole into the well to engage and change the state of the valve.After the formation isolation valve is closed, the well may be suspendedfor days or months.

A well intervention typically consumes a significant amount of time andmoney. Therefore, interventionless techniques have been developed tooperate the formation isolation valve. For example, a conventionalformation isolation valve may include a chamber that has prechargednitrogen, which acts as a gas spring for purposes of providing downholepower to operate the valve. More specifically, a control mechanism (aJ-slot-based mechanism, for example) of the valve, which limitsexpansion of the nitrogen is remotely controlled from the surface bymanipulating the well pressure. After a given sequence of well pressurefluctuations, the control mechanism allows the nitrogen to expand topush a piston for purposes of rotating a ball valve element of the valveopen.

A potential challenge in using the above-described formation isolationvalve with precharged nitrogen is that the gas chamber of the valvetypically is charged on the rig floor next to rig personnel before thevalve is run downhole and installed. In addition, under certain wellconditions, the well pressure may exceed the rating of the tools in thewell or the rating of the ball valve element during the sequence ofpressure fluctuations.

Thus, there exists a continuing need for better ways to remotely actuatea downhole tool, such as a formation isolation valve, for example.

SUMMARY

In an embodiment of the invention, a tool that is usable with a well mayinclude an operator, a switch, a spring and an indexer. The switchselectively communicates a first force to the operator to actuate thetool. The spring may be configured to exert a second force, and theindexer may cycle through a sequence of positions in response to thesecond force and a third force. The sequence of positions may includeone or more particular positions configured to cause the switch tocommunicate the first force to the operator in order to actuate thetool.

In another embodiment of the invention, a technique that is usable witha well includes transitioning an indexer of a tool through a sequence ofpositions in response to a force that is exerted by a spring. Thetechnique includes selectively communicating a force from a source otherthan the spring to an operator of the tool in response to the indexertransitioning to a predetermined position.

In another embodiment of the invention, a formation isolation valve thatis usable with a well includes a formation isolation valve element, anoperator and a seat. The operator actuates the valve element, and theseat is located in a central passageway of the formation isolation valveand is adapted to receive a flowable object to allow pressure in thecentral passageway above the object to increase to operate the operatorto actuate the valve element.

In yet another embodiment of the invention, a technique that is usablewith a well includes deploying a flowable object in the well to causethe object to lodge in a seat of a formation isolation valve that isdisposed in the well. The technique includes exerting fluid pressure onthe object to generate a force to actuate the formation isolation valve.

Advantages and other features of the invention will become apparent fromthe following drawing, description and claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram of a well according to an embodiment ofthe invention.

FIG. 2 is a schematic diagram of an actuator of a valve of the well ofFIG. 1 according to an embodiment of the invention.

FIGS. 3 and 4 are partial cross-sectional views illustrating operationof a valve according to another embodiment of the invention.

FIG. 5 is a flow diagram depicting a technique to actuate a valve usinga flowable object according to an embodiment of the invention.

DETAILED DESCRIPTION

In the following description, numerous details are set forth to providean understanding of the present invention. However, it will beunderstood by those skilled in the art that the present invention may bepracticed without these details and that numerous variations ormodifications from the described embodiments are possible.

As used here, the terms “above” and “below”; “up” and “down”; “upper”and “lower”; “upwardly” and “downwardly”; and other like termsindicating relative positions above or below a given point or elementare used in this description to more clearly describe some embodimentsof the invention. However, when applied to equipment and methods for usein wells that are deviated or horizontal, such terms may refer to a leftto right, right to left, or diagonal relationship as appropriate.

Referring to FIG. 1, an embodiment 40 of a formation isolation valve inaccordance with the invention controls access to a region of a well 10(a subsea well or a subterranean well) below the valve 40. In thisregard, the valve 40 is located downhole in a wellbore 20 and permitswell equipment, such as a tubular string (as a non-limiting example), topass through the valve 40 to the region beneath the valve 40 when thevalve 40 is in an open state. Conversely, when the valve 40 is in aclosed state, the valve 40 seals off fluid communication with the regionbeneath the valve 40.

In accordance with embodiments of the invention, the valve 40 may bepart of a string 23 that extends downhole through a wellbore 20. Thewellbore 20 may or may not be cased (via a casing string 22 forexample), depending on the particular embodiment of the invention.Furthermore, although the valve 40 is depicted as being in the verticalwellbore 20, the valve 40 may be disposed in a lateral or deviatedwellbore, in accordance with other embodiments of the invention. Anannular region, or annulus 25, which is located between an exteriorsurface of the valve 40 and the interior surface of the casing string 22(assuming the wellbore 20 is cased) may be sealed off by an annular sealor packer 34.

In general, the valve 40 includes a valve actuator 60 and a valveelement 44 that forms a controllable barrier for the valve 40. Asexamples, the valve element 44 may be a ball-type valve control elementor a flapper-type valve control element. Other types of valve controlelements are contemplated and are considered within the scope of theappended claims.

The actuator 60 operates the valve element 44 for purposes ofcontrolling the state (open or closed) of the valve element 44 (thus,controlling the state of the valve 40). In accordance with embodimentsof the invention described herein, the valve 40 is remotely operablefrom the Earth surface 11 of the well for purposes of avoiding anintervention to operate the valve. In this regard, in accordance withembodiments of the invention described herein, the actuator 60 of thevalve may be remotely operated by manipulating the pressure (hereincalled the “tubing pressure”) inside the string 23. More specifically,in accordance with embodiments of the invention described herein, thetubing pressure may be cycled up and down (via a surface pump (notshown), for example) for purposes of advancing an indexer of theactuator 60. After a predetermined number of up and down pressurevariations, the actuator 60 transitions the valve 40 to a predeterminedstate (e.g., transitions the valve from a closed state to an open state,for example).

As described below, unlike conventional remotely-operable formationisolation valves, the valve 40 does not contain a chamber that has ahighly pressurized gas, such as nitrogen. Instead, the valve 40 may relyon downhole well pressure, for example, the pressure exerted by fluid inthe tubing string 23 or the pressure that is exerted by fluid in theannulus 25, for purposes of providing a force able to drive the actuator60 to transition the valve 40 to a predetermined state. Therefore,instead of using a highly pressurized chamber to drive an indexer, thevalve 40 may include a relatively weaker mechanism, such as a resilientmember including but not limited to a mechanical coiled spring,belleville washers, leaf springs, and other resilient materials, forexample, for purposes of cycling the indexer through a predeterminedsequence of positions. In general, the indexer is part of a controlmechanism to control communication between an operator of the valve 40and the higher downhole pressure source (the pressure exerted by fluidin the well annulus or tubing string, for example) such that when theindexer reaches its final position, communication between the higherpressure source and the operator is established. This communication maycause the valve 40 to transition to the predetermined state (transitionthe valve 40 from a closed state to an open state, for example).

As a more specific example, FIG. 2 depicts a schematic diagram of theactuator 60 in accordance with some embodiments of the invention. Ingeneral, the actuator 60 includes a housing 100 that contains anoperator, such as an operator mandrel 80. The operator mandrel 80 isconstructed to axially translate to open and close the valve element 44(see FIG. 1) such that near the mandrel's bottom position (depicted inFIG. 2), the valve element 44 is open, and near its upper position, thevalve element 44 is closed.

In general, the operator mandrel 80 includes a piston head 82 thatresides inside a cavity 101 of the housing 100. The piston head 82divides the cavity 101 into an upper chamber 102 and a lower chamber104. Seals that are disposed on the piston head 82 and the housingprovide fluid isolation between the chambers 102 and 104. Fluidcommunication between the lower chamber 104 and a compensator 120, whichmay apply a well annulus pressure in some embodiments, is selectivelyestablished by a switch 144.

The piston head 82 has a piston head surface 83 to receive a force forpurposes of driving the operator mandrel 80 upwardly in response topressure in the lower chamber 104 when the switch 144 is open.

The upward movement of the operator mandrel 80 may be opposed by adownward force produced by fluid pressure (atmospheric pressure, as anon-limiting example) in the upper chamber 102 on an upwardly facingsurface 85 of the piston head 82. For example, in accordance with someembodiments of the invention, the force that is generated by the fluidpressure in the chamber 102 on the surface 85 may force the operatormandrel 80 to its bottom position to close the valve 40, in the absenceof the pressure-derived force (produced by the compensator 120) when theswitch 144 is closed.

For the following example, it is assumed that the valve 40 is closed,and the actuator, or operator mandrel 80, is moved for purposes ofopening the valve 40. However, as can be appreciated by one of skill inthe art, the valve 40 may likewise be transitioned from an open state toa closed state by a similar mechanism, in accordance with otherembodiments of the invention. In addition, in some embodiments othertypes of tools may be transitioned from a first configuration to asecond configuration, due in part to the translation of the operatormandrel 80.

In this illustrative embodiment, when the valve 40 is to remain closed,the piston head 82 is isolated from the well pressure via the switch144, which is located in a communication path between the compensator120 and the lower chamber 104. More specifically, as depicted in FIG. 2,the switch 144 may be disposed between a passageway 110 in communicationwith the lower chamber 104 and a passageway 140 in communication withthe compensator 120. The passageways 110 and 140 may be formed in thehousing 100.

Depending on the particular embodiment of the invention, the switch 144serves to selectively isolate the piston head 82 from the well pressureand thus, serves to selectively operate the operator mandrel 80,depending on whether the switch 144 is open or closed. Thus, in someembodiments of the invention, the switch 144 remains closed when thevalve 40 is closed, and the switch 144 is opened (as further describedbelow) in order to open the valve 40. In accordance with someembodiments of the invention, the switch 144 may be a type of valve,such as a pilot valve, among others.

The switch 144 is operatively coupled to an indexer 150, which directlyor indirectly controls the state (e.g., open or closed) of the switch144. The indexer 150 includes a housing 152 that houses elements of theindexer 150, such as an indexing mechanism 160 (a J-slot mechanism,among others for example) (the pattern formed on the side of theindexing mechanism in FIG. 2 is for illustrative purposes only and maynot be used as a limiting or only example of a functional pathway for anindexing mechanism), a piston head 170 and a mechanical spring 158 (acoiled spring, for example).

In general, the indexing mechanism 160 transitions through a sequence ofpositions in response to the cycling of the tubing pressure. Morespecifically, in accordance with some embodiments of the invention, thespring 158 generates an upward force on the piston head 170, which isconnected to the indexing mechanism 160. The upward force that isgenerated by the spring 158 is, however, countered by a downward forcethat is applied to an upwardly facing surface 174 of the piston head170. The downward force on the surface 174 may be exerted by wellpressure that is in communication with the surface 174 via openings 103and 154 in the housings 100 and 152, respectively.

In some embodiments, the well pressure may be in direct communicationwith the surface 174, or as illustrated in FIG. 2, the well pressure maybe in indirect communication with the surface 174 via a pressure device180. Pressure device 180 may include a cavity 181 separated into a firstchamber 184 and a second chamber 186 by a piston 182. The second chamber186 may be in communication with well pressure outside of the pressuredevice 180, either directly or indirectly (e.g., as through a resilientseal, among others). The first chamber 184 may be filled with clean oilor other type of fluid in order to reduce or prevent the contaminationand/or deterioration of the indexing mechanism 160. Pressure variationson one side of piston 182 (i.e., the side of the second chamber 186) maybe transmitted to the surface 174 of piston 170 via thenon-contaminating fluid. The piston 182 may be sealed in the cavity 181to prevent or inhibit fluid flow from one camber to the other.

The well pressure (e.g., either tubing or annulus pressure) may becycled up and downhole to correspondingly move the piston head 170. Themovement of the piston head 170 may cycle the indexing mechanism 160through a predetermined sequence of positions. For example, when thewell pressure increases to exert a downward force on the piston head 170that exceeds the upward force that is exerted by the spring 158, thepiston head 170 moves downwardly. When the tubing pressure is relaxed sothat the upward force generated by the spring 158 exceeds the downwardforce that is exerted by the well pressure, the piston head 170 movesupwardly. In accordance with embodiments of the invention, each up anddown cycle of the piston head 170 may cause the indexing mechanism 160to transition to the next position of the sequence.

In some embodiments, the well pressure is determined as a differencebetween the annulus pressure and the tubing pressure. For example, ifthe housing 100 has an orifice 156 either directly or indirectlycommunicating with tubing pressure, then the pressure device 180 may bedirectly or indirectly communicating with annulus pressure. In such asituation, the piston head 170 may move when the annulus pressureexceeds the tubing pressure plus the force of the spring 158. Of course,the pressure device 180 may be actuated by tubing pressure and orifice156 may communicate with annulus pressure. Even further, in someembodiments, housing 100 may not comprise orifice 156 and the cavitysurrounding spring 158 may contain a compressible fluid (e.g., air orsome gas) at atmospheric pressure.

Eventually, the indexing mechanism 160 reaches a position that permitsthe mechanism 160 to axially shift to a position that actuates switch144. For example, the indexing mechanism 160 may be connected to asleeve that has a constrained degree of travel (via a pin and “J-slot”arrangement of the indexing mechanism 160, as a non-limiting example)until the indexing mechanism 160 reaches a position that allows thesleeve to travel beyond its restrained limit to open a port to establishcommunication between the passageways 140 and 110.

In some embodiments of the invention, further cycling of the tubingpressure may be used to cycle the indexing mechanism 160 back to aposition in which the mechanism 160 closes the switch 144. Otherswitches, switching mechanisms, indexing mechanisms, etc. may be used,in accordance with other embodiments of the invention.

Additionally, some illustrative embodiments may comprise an indexlocator 161. During shipping of downhole tools, the indexing mechanism160 may become offset from a position as initially manufactured.Therefore, an index locator 161 may be read at the well site prior tolowering the tool into the well. By using the index locator 161, a welloperator may determine the number of pulses or cycles needed to set theindexing mechanism 160 to an actuating position.

The index locator 161 may be any device, component, or method used todetermine the position of the indexing mechanism 160 without having todisassemble the tool. Examples of index locators 161 may include, butare not limited to, magnetic materials or fields (e.g., using halleffect sensors for example), radio frequency identification devices(e.g., RFID tags), or dissimilar materials (e.g., a metal or radioactivepin in a non-metallic indexing mechanism 160), among others. By using areading device external to the housing 100, a technician may be able todetermine the location of a magnetic or ferro-magnetic material, therebyindicating the amount of rotation or relative position of the indexingmechanism 160 within the housing 100.

In an exemplary embodiment of the invention, a compensator 120 may beprovided to actuate the operator mandrel 80. The compensator 120 maycomprise a chamber 130 that contains relatively clean oil 132. Afloating piston 124 may be sealably disposed in the chamber 130 anddefine a movable boundary between the oil 132 and direct or indirectcontact with the pressure of the well fluid. A downwardly facing surface127 of the piston 124 may be in contact with the oil 132, and anupwardly facing surface 125 of the piston 124 may directly or indirectlycommunicated with the well pressure. Thus, the piston 124 transmits thepressure that is applied by the well fluid in the annulus or tubing tothe oil 132. Accordingly, the oil 132 communicates this pressure to thepiston head 82 of the operator mandrel 80 when the switch 144 is open.

In accordance with other embodiments of the invention, a downhole tool,such as formation isolation valve, may be operated using a flowableobject, such as a ball or a dart. In this regard, the flowable objectmay be deployed in the well (from the Earth surface 11 (see FIG. 1) ofthe well, for example) and descend through the well until the objectlodges in a seat of the tool. Once lodged in the seat, fluid pressuremay be increased above the lodged flowable object to subject the object,and any structure interacting with the object, to a force that operatesthe tool.

As a more specific example, FIG. 3 depicts a partial schematic diagramof a downhole tool 300 in accordance with an embodiment of theinvention. It is noted that FIG. 3 depicts a right hand partialcross-section of the valve about a longitudinal axis 330 of the tool300. It is understood that the tool 300 includes a mirroring left handcross-section, as the tool 300 is generally symmetric about thelongitudinal axis 330, as can be appreciated by one of skill in the art.

FIG. 3, in general, depicts the tool 300 in an unactuated state. In thisregard, the tool 300 includes an operator mandrel 320 that is to bemoved in a downward direction to transition the tool 300 to the nextdesired state. It is noted that the operator mandrel 320 may include, asexamples, one or more piston heads for purposes of retaining the mandrel320 in the position depicted in FIG. 3. Alternatively, releasablemechanical fixtures, such as shear pins, may secure the operator mandrel320 to a housing 304 of the tool 300, or as yet another example, theoperator mandrel 320 may be secured to a mechanical section 310 that maybe used to operate the mandrel 320 via an alternative mechanism.

In this regard, in accordance with some embodiments of the invention,the tool 300 may be remotely operated from the surface of the well ormay be operated via an intervening tool. It is possible that during thelifetime of the tool 300, the tool 300 does not operate as intended,thereby resulting in the use of a backup control, such as the usage of aflowable object, for example. However, the control scheme that isdescribed in connection with FIGS. 3, 4 and 5 may be a primary controlfor the tool 300 or a backup control for the tool 300.

For the example depicted in FIG. 3, the flowable object is a ball 324that is deployed in the well and lodges in a valve seat 321 that isformed near the top of the operator mandrel 320. When the ball 324 abutsagainst the seat 321, the ball 324 substantially restricts fluidcommunication through a central passageway of the tool 300. As a result,fluid may be introduced from the surface of the well for purposes ofincreasing downward pressure on the ball 324. This increased pressure,in turn, produces a downward force on the ball 324 and correspondinglyon the operator mandrel 320. Eventually, the force increases to a pointat which the downward force is sufficient to move the operator mandrel320 in a downward direction and thus, actuate the tool 300. The actuatedstate of the tool 300 is depicted in FIG. 4.

After the tool 300 is actuated, various techniques may be used to removethe ball 324 from the seat 321 after the tool 300. As examples, an acidor other dissolving fluid may be introduced into the well to dissolvethe ball 324; the ball 324 may be frangible and thus, may be fragmentedby a direct impact (via a tool) or by acoustic energy (as a non-limitingexample); reverse circulation may be used by opening circulation portsin the string above the tool 300 to circulate the ball 324 back to thesurface of the well; etc.

Depending on the particular embodiment of the invention, the tool 300may be an isolation valve (a formation isolation valve, for example).However, the tool 300 may be another type of valve (a sleeve valve, forexample) or another type of downhole tool, such as a packer, flowcontrol device, etc. Many variations and types of tools are contemplatedand are within the scope of the appended claims.

To summarize, FIG. 5 depicts a technique 400 in accordance withembodiments of the invention. Pursuant to the technique 400, a flowableobject is deployed in a well, pursuant to block 404. The flowable objectlodges (block 408) in a seat of a formation isolation valve and apressure is exerted on the ball to move an operator mandrel to change astate of the valve, pursuant to block 412. Other variations arecontemplated and are within the scope of the appended claims.

While the present invention has been described with respect to a limitednumber of embodiments, those skilled in the art, having the benefit ofthis disclosure, will appreciate numerous modifications and variationstherefrom. It is intended that the appended claims cover all suchmodifications and variations as fall within the true spirit and scope ofthis present invention.

1. A tool usable in a well, comprising: an operator having a headdisposed within a cavity of a housing of the tool, the cavity beingselectively supplied with hydraulic fluid through a passageway; a switchpositioned in the passageway to selectively communicate a first force tothe operator to actuate the tool by opening the passageway to flow ofthe hydraulic fluid; a compensator coupled to the passageway to supplythe hydraulic fluid under pressure via a compensator piston exposed towell pressure in a surrounding annulus; and an indexer operated by apiston head exposed to a force generated by well pressure on one sideand to an opposed force generated by a resilient member on the otherside, the indexer being able to cycle through a sequence of positions inresponse to the force and the opposed force, the sequence including aposition to cause the switch to open the passageway to flow of thehydraulic fluid to shift the operator.
 2. The tool of claim 1, whereinthe first force comprises a force produced by fluid in the surroundingannulus disposed within a casing in the well.
 3. The tool of claim 1,wherein the first force comprises a force produced by fluid in anannulus of the well.
 4. The tool of claim 1, wherein the tool comprisesa valve, and the operator comprises a mandrel to operate a valve elementof the valve.
 5. The tool of claim 4, wherein the valve is a formationisolation valve.
 6. The tool of claim 1, wherein the resilient membercomprises a mechanical spring.
 7. The tool of claim 4, wherein a centralpassageway of the valve further comprises a seat configured to interactwith a flowable object so as to facilitate the production of the firstforce in the central passageway.
 8. The tool of claim 1, furthercomprising an index locator configured to correlate to a position of theindexer in the sequence of positions.
 9. The tool of claim 8, whereinthe index locator comprises a magnetic field.
 10. A method usable with awell, comprising: coupling an operator with a compensator via apassageway containing hydraulic fluid, the compensator being acted on bywell pressure in a wellbore; controlling flow of the hydraulic fluidthrough the passageway with a switch; connecting the switch to anindexer; selectively opening the switch by transitioning the indexerthrough a sequence of positions in response to sequential opposingforces exerted by a resilient member and at least one other force from asource other than the resilient member, the selectively opening causingmovement of the operator via flow of the hydraulic fluid through thepassageway; and actuating a formation isolation valve through movementof the operator.
 11. The method of claim 10, further comprising:deploying a flowable object into the well; and generating the operatingforce due to an interaction between the flowable object and theformation isolation valve.
 12. The method of claim 10, furthercomprising: deploying a flowable object into the well; seating theflowable object in a central passageway of the formation isolationvalve; and generating the operating force due to the seating of theflowable object and the formation isolation valve.
 13. A method ofdetermining a position of an indexer in a sequence of positions, themethod comprising: providing an index locator coupled to the indexer;detecting a location of the index locator; and indicating the locationof the index locator to a point external from a housing of the indexer.14. The method of claim 13, in which the index locator generates amagnetic field.
 15. A method usable with a well, comprising: deploying aflowable object in the well; interacting the flowable object with aformation isolation valve disposed in the well; and generating a forceto actuate the formation isolation valve due to the interaction betweenthe flowable object and the formation isolation valve.
 16. The method ofclaim 15, wherein the interacting comprises abutting the flowable objectagainst a seat in a central passageway of the formation isolation valve;and wherein the generating of the force comprises building fluidpressure above the formation isolation valve